Leighton Meester on Mom's Lawsuit: Get Outta Town!

The actress has filed a petition with Los Angeles Superior Court asking a judge to throw out Constance Meester's lawsuit - for $3 million, citing breach of contract - as a "matter of law" on the grounds that the allegations are frivolous.

The very notion that the star had an oral contract to pay her mother $10,000 a month for life is ridiculous, they say, and the fact that Leighton has been giving her money up until now - $7,500 a month in fact - means nothing.

"None of these agreements are valid or enforceable as a matter of law," the filing states.

The 25-year-old actress sued her mom in July in order to have a judge declare that there never was any oral agreement and was promptly sued back.

Leighton says she voluntarily gave Constance $7,500 a month to provide medical care for her younger brother, Lex, who had brain surgery last May.

She says Constance used the cash for, among other things, procedures including "plastic surgery on her face and stomach, Botox and hair extensions."